Maintenance of multiple copies of data is part of the security function in data processing operations in case data is unavailable, damaged, or lost. Institutional users of data processing systems commonly maintain quantities of highly important information and expend large amounts of time and money to protect data against unavailability resulting from disaster or catastrophe. One class of techniques for maintaining redundant data copies is termed mirroring, in which data processing system users maintain copies of valuable information on-site on a removable storage media or in a secondary mirrored storage site positioned locally or remotely. Remote mirroring off-site but within a metropolitan distance, for example up to about 200 kilometers, protects against local disasters including fire, power outages, or theft. Remote mirroring over geographic distances of hundreds of kilometers is useful for protecting against catastrophes such as earthquakes, tornadoes, hurricanes, floods, and the like. Many data processing systems employ multiple levels of redundancy to protect data, positioned at multiple geographic distances.
One of the challenges in management of large database and storage networks is maintenance and growth of connectivity to an amorphous fabric structure that is constantly changing, adding more capacity, modifying capabilities, and addressing failures that can occur at any point in the system. Current disk mirroring technology generally employs dedicated Fibre Channel (FC) or Enterprise Systems Connection (ESCON) links between storage arrays, with all the restrictions and limitations imposed by and inherent to FC and ESCON.